The Nonstress Test During Pregnancy

Don't worry — it's not stressful. The nonstress test is a third trimester check of your baby's well-being.

Stocksy

A nonstress test (NST) measures fetal heart rate and response to movement in the third trimester to ensure your baby's doing well and getting enough oxygen.

Who the nonstress test during pregnancy is for

A nonstress test is generally ordered when a mom has a complication like gestational diabetes or preeclampsia or a procedure like amniocentesis. You also might get one if your baby is measuring small for his gestational age or isn't very active. And you might have an NST if your due date passes but your baby stays put.

When you might get a nonstress test

What happens during a nonstress test

A stretchy belt monitor will be placed around your belly (the same kind doctors often use during labor and delivery). No mindless magazine-flipping for you — you've got a job to do: You'll be asked to keep track of each movement you feel baby make. You may hold a clicker contraption (like a buzzer on Jeopardy) and each time you feel the baby move, you'll click it, though other fetal monitors may work differently. The test lasts 20 to 40 minutes.

What the nonstress test results mean

A baby who moves a lot and has a normal heart rate is classified as "reactive" — i.e. healthy and not under any stress.

A "nonreactive" baby is one who does not make a minimum number of movements during the 40-minute period or whose heart doesn't accelerate as much as expected when he does move. A nonreactive result does not necessarily mean your baby is in danger. However it could mean your baby isn't getting enough oxygen. Technicians will make a noise over your belly or offer you a sugary drink to encourage your baby to move, or the test may be done for another 40 minutes. If your practitioner determines that your baby could be under stress, she'll order further testing (like a biophysical profile) to determine if labor induction and early delivery are necessary.

From the What to Expect editorial team and Heidi Murkoff, author of What to Expect When You're Expecting. Health information on this site is based on peer-reviewed medical journals and highly respected health organizations and institutions including ACOG (American College of Obstetricians and Gynecologists), CDC (Centers for Disease Control and Prevention) and AAP (American Academy of Pediatrics), as well as the What to Expect books by Heidi Murkoff.

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